Attenuation lengths of high energy photoelectrons in compact and mesoporous SiO2 films

We have experimentally evaluated attenuation lengths (AL) of photoelectrons traveling in compact and micro and mesoporous (~ 45% voids) SiO2 thin films with high (8.2–13.2 keV) kinetic energies. The films were grown on polished Si(100) wafers. ALs were deduced from the intensity ratio of the Si 1s signal from the SiO2 film and Si substrate using the two-peaks overlayer method. We obtain ALs of 15–22 nm and 23–32 nm for the compact and porous SiO2 films for the range of kinetic energies considered. The observed AL values follow a power law dependence on the kinetic energy of the electrons where the exponent takes the values 0.81 ± 0.13 and 0.72 ± 0.12 for compact and porous materials, respectively.